The present invention is particularly a modification of or an improvement over the arrangements disclosed in U.S. Pat. No. 5,232,405 issued Aug. 3, 1993 and U.S. Pat. No. 5,482,508 issued Jan. 6th, 1996 of the present inventors, the disclosures of which are incorporated herein by reference.
These arrangements show blades which include a support plate lying in a radial plane and an additional plate or flap at right angles to the support plate so that the additional plate lies longitudinally of the hub. The additional plate is in most cases inclined so that a radially outer edge of the additional plate lies angularly forwardly of a radially inner edge of the plate. The additional plate is welded across a trailing edge of the support plate and extends out to both sides of the support plate.
These arrangements have achieved considerable commercial and technical success and the present invention is directed to a yet further improvement which builds upon the improvement of the previous patent.
A further arrangement relevant to the present invention is that shown in U.S. Pat. No. 5,042,973 of Hammarstrand which discloses a similar chopping and discharge apparatus having rotating blade members carried on a hub and stationary blades fixed to the housing. The blade members are mounted in pairs so that a single lug carried on the hub supports a transverse pin parallel to the axis of the hub with the blade members mounted on respective sides of the lug and carried on bushings mounted on the pin. The blade members are spaced so that each blade member passes between two of the stationary blades in a cutting action. The blade members are shaped so as to be arch shaped in each cross section transverse to the length of the blade member thus defining a sharpened cutting edge at the leading edge and a sharpened cutting edge at the trailing edge with a center section of the blade bowed outwardly of a plane containing the leading and trailing edges. The blades are shown in face to face or back to back arrangements of the pairs.
A yet further arrangement is shown in U.S. Pat. No. 3,693,335 (Mathews) which shows blades which are inclined from the normal radial plane so as to extend outwardly from the hub in a direction which is inclined to the radial and axial directions.
A yet further arrangement is disclosed in U.S. Pat. No. 4,292,795 (Linn) issued Oct. 6th, 1981 and U.S. Pat. No. 4,892,504 (Scott) issued Jan. 9th, 1990 both of which show a straw spreader which includes a horizontal fan assembly with two types of blades which rotate about parallel vertical axes on top of a base plate and generate a suction effect tending to draw the straw downwardly into the top of the fan assembly and to expel the straw rearwardly from the back of the base plate.
In the above U.S. Pat. No. 5,482,508 of the present inventors, the blades are arranged with some flat blades and some bent fan blades so as to generate an air flow across the full width of the cutting assembly. Attempts have been made to modify the arrangement of the flat cutting blades relative to the fan blades so that there are more fan blades adjacent the ends of the cutting assembly so as to increase air flow at the ends where the larger air flow is required to effect spreading of the material from the ends of the cutting assembly. However this action of increasing the number of fan blades at the ends has not allowed the arrangement to provide an effective cutting action to provide the shortest straw which can be achieved using solely flat blades.
One attempt to improve air flow is that shown in U.S. Pat. No. 6,113,491 issued Sep. 5th, 2000 by Holmen which discloses a cutting assembly having conventional flat blades with a fan arranged at one end of the cutting assembly and arranged to drive the air inwardly and into an opening in the housing so that the air is released along the length of the cutting assembly at the flat cutting blades to assist in driving the air and the material out of the cutting assembly. This arrangement has not achieved significant commercial success.
Another attempt to improve air flow is that shown in U.S. Pat. No. 4,637,406 issued Jan. 20th, 1987 by Guinn in which Hesston discloses a cutting assembly which includes fan blades within the rotor assembly attempting to drive air through the rotor and out with the cut material.
In U.S. Pat. No. 6,070,816 issued Jun. 6th, 2000 by Hirsch, Deere discloses an arrangement in which there is provided two vertical rotors side by side, each having internal additional fan blades within the rotor which assist in discharging the material.
In U.S. Pat. No. 5,833,533 issued Sep. 17th, 1996 by Roberg, Claas discloses a further arrangement in which a conventional horizontally mounted chopping rotor is supplemented by two fan members lying underneath the discharge of the rotor.
Both of these arrangements are very complicated and significantly increase the cost of the construction.
In U.S. Pat. No. 4,923,431 (Miller) issued May 8th, 1990 and U.S. Pat. No. 4,137,923 (Druffel) issued Feb. 6th, 1979 are disclosed arrangements in which chaff is spread using fans arranged at the ends of the chaff discharge so that each fan is directed to blow the material out to the side of the combine harvester.
In many cases, an improved spreading action is required requiring the use of fan blades or flails as disclosed in the above patents of Redekop. However these arrangements require relatively wide spacing between the stationary blades due to the increased width of the flails or fan blades. A further requirement in some cases is therefore that the length of the chopped pieces be reduced as far as possible. These two requirements of providing increased air flow and providing minimum cutting length are therefore contrary requirements and up until now the only arrangements available to carry out this minimum cutting length and sufficient spreading action are the complicated arrangements provided by Deere or Claas and set forth above in which additional spreading action is provided to supplement the weak spreading action provided by the narrow cutting blades.